Such intraocular lenses are known. The first and second main lens surface constitute a main lens together with the material of the optic. The main lens is generally optimized for distance vision of the person having the IOL inserted in the eye and will correct for any optical errors of the eye to provide a project a good quality image of a distant object on the retina. The first additional power part generally is laid out to provide near or distance vision. It may be embodied as a sector in between the main optical axis and the circumference of the optic, which may take about half of the surface area of the optic at the first side, although other embodiments may be envisaged as well.
However, when someone is reading, especially at low light conditions, his or her pupils will become narrower. The effect of the first additional optical active part (reading part) will therefore become less effective for a person having an IOL inserted in the eye. This effect even becomes worse for persons having narrow pupils anyway. In such circumstances and especially for persons having narrow pupils the effect of the first additional power (reading) part may effectively be absent or only be very weakly present. Only distance vision remains available, which is a very unfavorable situation.